1. Field of the Invention
The present invention relates to a device for converting photons into charge packets, and more particularly to an image sensor with a metal wiring and a method of manufacturing the image sensor.
2. Description of the Prior Art
An image sensor is a device for converting one or two-dimensional optical image into an electrical signal. The image sensor is a kind of a solid-state image sensor which is generally divided into a CMOS (Complementary Metal Oxide Semiconductor) image sensor and a CCD (Charge Coupled Device) image sensor.
The CMOS image sensor converts an optical image into an electrical signal, and employs a switch mode to detect outputs one by one using MOS transistors which are made as many as the number of pixels by use of CMOS manufacturing technique. In particular, the CMOS image sensor has advantages in that a driving mode is simple, various scanning modes can be embodied, and a signal processing circuit can be integrated into a single chip, which can miniaturize a chip. In addition, the CMOS image sensor is inexpensive and consumes a low power, because of utilizing a compatible CMOS technique.
The CMOS image sensor generally includes a pixel array and a peripheral circuit. In particular, the pixel array mainly consists of a photodiode for receiving incident light and a peripheral cell for converting the received light into an electrical signal. The photodiode has to secure a region occupied by the photodiode to receive much light.
In the case of securing the occupied region, there is a problem in that the pixel array is largely sized. In addition, since the region occupied by the pixel array is determined after a peripheral cell region is secured, there is a limitation of reducing a size of the pixel array. Accordingly, a fill factor (i.e., a ratio of the photodiode to the pixel array) is up to 30% at present.
Such as, a conventional CMOS image sensor has some advantages, but it is difficult to enlarge an area to be occupied by the photodiode, which may not obtain an image of high resolution.